The uptake of radioactive phosphorus by brown trout (Salmo trutta L.) from water and food

Brown trout were exposed to P-32 in their tank water (7.4 Bql(-1)) and the uptake to muscle followed over 6 weeks. A steady-state concentration factor (C-ss) of 1.7 and a biological half-time for clearance (t(b1/2)) of 45 clays were calculated from the results. The low C-ss indicates that uptake from water is not a major route of P-32 accumulation in these fish. Brown trout were given a single P-32-spiked meal, and the uptake and clearance in muscle, liver and blood followed over 6 weeks. Assimilation of the isotope by these organs was low, the maximum activity in whole muscle reaching only 0.2-0.4% of that in the meal with lower values in the other two organs. There was no appreciable clearance of P-32 from muscle during the experiment. The slow clearance of P-32 after uptake front water and lack of any clearance after uptake from food indicates that the C-ss for this isotope following uptake by either route is likely to depend on radioactive decay rather than intake rate and physiological clearance. Crown Copyright (C) 1998 Elsevier Science Ltd.